Any member of the police department who becomes incapacitated for the performance of his duty by reason of bodily injury received in, or illness caused by performance of his duty, shall be retired. If he is not qualified for service retirement, he shall receive a retirement allowance in an amount which shall be equal to the same percentage of the final compensation of said member, as defined in Section 8.545, as his percentage of disability is determined to be. The percentage of disability shall be as determined by the Workers' Compensation Appeals Board of the State of California upon referral from the retirement board for that purpose; provided that the retirement board may, by five affirmative votes, adjust the percentage of disability as determined by said appeals board; and provided, further, that such retirement allowance shall be in an amount not less than 50 percent nor more than 90 percent of the final compensation of said member, as defined in Section 8.545. Said allowance shall be paid to him until the date upon which said member would have qualified for service retirement had he lived and rendered service without interruption in the rank held by him at retirement, and after said date the allowance payable shall be equal to the retirement allowance said member would have received if retired for service on said date, based on the final compensation as defined in Section 8.545 he would have received immediately prior to said date had he lived and rendered service as assumed, but such allowance shall not be less than 50 percent of such final compensation. If at the time of retirement because of disability, he is qualified as to age and service for retirement under Section 8.546, he shall receive an allowance equal to the retirement allowance which he would receive if retired under Section 8.546 but not less than 55 percent of said final compensation. Any member of the police department who becomes incapacitated for the performance of his duty, by reason of a cause not included under the provisions of the immediately preceding sentences, and who shall have completed at least 10 years of service in the aggregate, computed as provided in Section 8.554 shall be retired upon an allowance of one and one-half percent of the final compensation of said member, as defined in Section 8.545, for each year of service provided that said allowance shall not be less than 331/3 percent of said final compensation; provided, however, that if such member has completed at least 25 years of service in the aggregate, computed as provided in Section 8.554, but has not yet attained the age of 50 years, he shall receive an allowance equal to the retirement allowance he would have received if he had attained the age of 50 years and retired under Section 8.546 as of the date of retirement for such incapacity. The question of retiring a member under this section may be brought before the retirement board on said board's own motion, by recommendation of the police commission, or by said member of his guardian. If his disability shall cease, his retirement allowance shall cease, and he shall be restored to the service in the rank he occupied at the time of his retirement.